Projection system

Abstract

Provided is a projection system capable of obtaining a sharp contrast without being influenced by an ambient light, the projection system including a projection screen, containing a substrate and a polarized light selective-reflection layer formed on the substrate that diffuse-reflects right-handed circularly polarized light or left-handed circularly polarized light. An image is displayed by reflecting an image light irradiated from a projector on the projection screen. An external light screen is installed at an external light entrance and disposed in a sequence of a linearly polarizing plate and a retardation plate from an external side, and the external light screen circularly polarizes a light in reverse direction to the circularly polarized light diffuse-reflected by the polarized light-selective reflection layer. A transmission axis of the linearly polarizing plate is in a horizontal direction.

Description

BACKGROUND OF THE PRESENT INVENTION[0001]1. Field of the Present Invention[0002]The present invention relates to a projection system comprising a projection screen, a projector, and an external light screen.[0003]2. Description of the Related Art[0004]A conventional projection system is generally designed to display an incident image light, from a projector, on a projection screen, and an observer observes its reflected light as an image.[0005]Recently, along with downsizing, price-reduction, etc. of the projector main body, demand for use at home, such as home theater system, is increasing, and the projection systems are widely used in general household. In such projection system, image contrast of an image is brought forth by intensity difference of the incident light (image light), from the projector, incident on the projection screen. For example, when displaying a white picture on a black background, the portion of the projection screen lighten by the incident light will be whi...

AI Technical Summary

Benefits of technology

The present invention provides a projection system that can obtain a sharp contrast display without being influenced by the ambient light. The system includes a polarized light selective-reflection layer and an external light screen. The polarized light selective-reflection layer diffuse-reflects right-handed or left-handed circularly polarized light, and the external light screen circularly polarizes the light in reverse direction to the reflected light. This results in a theoretically set reflection of external light on the projection screen to zero, allowing only the image light to be reflected. The external light screen also takes in a brighter environment within a range not adversely influenced by the ambient light. The invention provides a display of sharp contrast and improved image quality.

Problems solved by technology

As a result, in such conventional projection screen, it is difficult to realize a favorable image display unless influence by the ambient light such as external light is suppressed by using a means to darken the room or other environmental means.

However, it does not have polarized light selectivity, and there is a problem that it can only display an image with sharpness of limited degree.

Further, there is a problem that, in the projection screen using hologram, it is difficult to obtain a wide screen because of manufacturing problem.

However, for example, even when the cholesteric liquid crystal, which reflects right-handed circularly polarized light, is used, the right-handed circularly polarized light of the ambient light is reflected, so that sufficient improvement of the contrast cannot be realized in some cases.

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